Over the years, power distribution systems have been developed which distribute power from various types of power generation facilities and eventually to end users such as residential and commercial customers. Various regulated power utility companies have been primarily responsible for the power generation facilities and for the power distribution system or network which distributes the power to customers. Because many of these power utility companies have been granted monopoly or monopoly like rights over the years, for example, and because little or no competition previously existed, these utility companies often have been reluctant or quite slow to change. As various power utility companies have become more competitive with each other and as the power utility companies have become more deregulated in more recent years, change in technology has increased.
One of the areas associated with these power utility companies where change has been slow is with the power distribution systems. Power is still primarily distributed from power generation facilities or intermediate power stations to residential and commercial customers by the use of overhead power line networks, e.g., often three-phase power line networks. As used herein, an upstream direction along a power line will generally be in a direction toward a power generation facility or power source, and a downstream direction along a power line will generally be in a direction toward a customer, e.g., residential or commercial, or other user of power.
One recurring problem with these overhead power line networks, for example, is the maintenance and repair associated with ensuring that customers receive power when desired and continuously. Another recurring problem, for example, is the increased risk of injury to service or maintenance workers when working on either the power lines themselves or systems and devices associated with the power lines.
The power line network is conventionally a three-phase power line network, and this description is applicable to each of the three power lines. For simplicity, however, only one of the three power lines is described for this process. To service or repair only a portion of a power line network or system, for example, an upstream switch associated with the power line network needs to be opened, e.g., the switch breaks the downstream load. The opening of the switch causes all customers downstream from the switch to have at least a temporary power loss. Permanent jumper cables connected to a power line pole and to the power lines then need to be cut while the power load is not being transmitted across that portion of the power lines, e.g., the lines are "cold", and then the switch is closed. If the permanent jumper is cut while the full power load is being transmitted across the power lines, e.g., the lines are "hot", then severe arcing and potential increased risk of injury to the workers and surrounding equipment can occur. The power line pole acts like an end node for the network so that power is once again available to those customers downstream from the switch and up to the power line pole where the permanent jumper(s) are cut. Utility workers can then repair or work on the segment of the network downstream from the power line pole where the permanent jumper(s) are cut.
In order to restore power to the repaired or serviced section of the power line network, the upstream switch is again opened causing all of the downstream customers to lose power, and the permanent jumper is reattached to the power line pole connection. The upstream switch is then closed once again restoring power to the downstream customers to both the portion from the switch to the power line pole and to the customers downstream from the power line pole where the service or repair has occurred.
One alternative to the above conventional procedure that has developed is to provide a temporary jumper cable which connects to the power line and extends around the power line pole connected to each of two separate segments or portions of a power line network. The permanent jumper cables can then be cut, and a power line switch positioned upstream from the power line pole can then be opened. The temporary jumper cable can then be removed, and the upstream power line switch can be closed again. Utility workers can then repair or work on the segment of the network downstream from the power line pole where the permanent jumper(s) are cut. This allows cold operation on the segment of the network downstream from the power line pole. The process is reversed to restore power to the repaired segment of the power line. This alternative, however, is not much different than the other conventional approach described above.
Another alternative that has developed is to use temporary load pick-up jumper cables for the operation. In this process, the upstream power line switch is opened causing a loss of power to all of the downstream customers, and the permanent jumper is cut. The upstream switch is then closed, and only the segment of the power line network downstream from the cut permanent jumper is cold. The repair is made, and then the temporary load pick-up jumper cables can be connected to the power lines and extend around the power line pole with the cut permanent jumper while the upstream segment of the network is hot and the downstream segment is cold. This restores power to the segment of the network downstream from the power line pole. The permanent jumper can then be reattached, and then the temporary load pick-up jumper cables removed. Although this approach may be somewhat helpful, all customers downstream from the upstream power line switch still temporarily lose power even though nothing may be wrong with their corresponding segment of the network.